Traditional buildings: energy efficiency & climate change
What are traditional buildings?
Traditional buildings were built in construction methods passed down over many generations. Those which survive in the Darlington borough generally have solid brick or stone walls laid and (originally) pointed in lime mortar. They perform very differently to modern constructions (e.g. cavity walling), as they are made of permeable materials which allow moisture movement within the fabric, so that they can dry out. Natural ventilation and heating also play a crucial role in the drying-out processes of traditional structures.
The importance of recognising the difference between traditional solid-wall and modern buildings cannot be overemphasised. If you are unsure whether you have a traditional structure, you should look at the following:
- Wall thickness: External solid stone walls are often around 60cm (2ft) thick, whilst modern cavity walling is around half the thickness. However, some later traditional buildings (from the late-Victorian period on) may have thinner external solid walls.
- Brick bonding: External solid brick walls display both header and stretcher bonds (whereas modern cavity walling generally only has stretchers).
- Lime products: Look whether you can find any traces of lime mortar, lime render, haired lime plaster, or lime wash on your walls, partitions or ceilings. Lime products are often quite white in colour and can include distinct coarse aggregate. Critically, they are more porous/softer than modern substitutes like cement, which is why they dry out easily.
Also note that traditional structures possess varying degrees of heritage significance.
Society for the Protection of Ancient Buildings (SPAB) - Lime [external link]
What challenges do traditional buildings face?
Traditional structures have performed well for thousands of years, and their survival is testament to their longevity. Historically, houses were designed so that they could be heated and dried out efficiently, whilst building parts which were not supposed to be warm (e.g. dairies and pantries) were kept naturally damp and cool. Such traditional approach is sustainable and has a low carbon footprint, especially when local materials have been used.
Since the mid-twentieth century, dense, high-carbon materials like cement have increasingly been applied to traditional buildings, with little awareness that these are incompatible with solid-wall structures. The long-term consequences of such interventions are often damp problems, resulting in cold walls with poor insulating properties.
Energy Performance Certificates (EPCs) frequently don’t reflect the true performance of a building as they tend to overestimate energy use for older and underestimate it for newer buildings. Erroneous ratings are provided because their calculation is based on certain assumptions rather than site-specific data. EPCs also include standard recommendations for 'improving' the energy efficiency of buildings that can actually be harmful to them.
User behaviour has changed since traditional buildings were constructed. They were designed with practicality in mind, but now modern trends are often perceived to be more important, leading to alterations to its fabric or user habits which can cause problems.
- One example would be original ‘small’ rooms of houses which enabled heating them very efficiently. In the twentieth century open-plan living became fashionable so partitions were pulled down to create larger rooms, but these are more difficult to heat, ventilate and, consequently, dry out.
- Another example would be the exposure of stonework by removing plasters or renders for aesthetic reasons. This reduces the wall’s ability to deal with moisture, potentially increasing dampness and decreasing indoor comfort levels.
Today, additional threats have been linked to climate change. Traditional buildings will increasingly be exposed to more severely fluctuating weather (rainfall is becoming less frequent though more intense in the UK). It is unclear how well they will cope as historical structures and materials are more used to gradual, rather than rapid, change of conditions. Nevertheless, it has been argued that the thermal mass of traditional solid walls is important for addressing climate change as it helps to regulate temperatures.
Historic England (2021) Mapping Climate Hazards to Historic Sites [external link]
IHBC@COP26: Conserving our Places Conserves our Planet! - Podcasts [external link]
How we measure energy efficiency in homes isn’t working[external link]
What is retrofitting?
Retrofitting means that existing building fabric is altered or added to with new materials with the intention of improving the building’s performance; it does not include the introduction of the new building services or alternative sources of energy generation (e.g. solar panels). The aim is to prevent excessive heat loss from the building, although traditional solid walls do require some heat to travel to the exterior so that they can dry out.
The intended outcomes of retrofitting are saving money and providing higher comfort levels on an individual basis, as well as working globally towards a ‘net zero’ (carbon neutral) future, to reduce the impacts of climate change. When assessing the amount of carbon emissions of a building, it is crucial that the whole-life carbon footprint is taken into account:
- Pre-construction emissions (tests, studies, design, land acquisition, etc.)
- Product emissions (raw materials supply, transport, manufacturing)
- Construction emissions (excavation, building, fitting)
- In-use emissions (materials/services in use, maintained, repaired, replaced, refurbished)
- Operational emissions (water and energy used to run the building)
- End-of-life emissions (demolition, transport, waste processing, disposal)
- Circular economy emissions (reuse, recycling of materials/services)
It has been recognised that the conservation of the historic built environment is an essential component of the response to the threat posed by climate change and long-term planning for sustainable development. Consequently, reusing and upgrading an existing building has a much lower whole-life carbon footprint than demolishing it and constructing a new one in its place.
IHBC@COP26: Conserving our Places Conserves our Planet! - Podcasts [external link]
Before considering what to do with your building, you will need to consider the following:
- Construction type of your property. First of all, you will need to find out whether you have a traditional or modern building (see above). This is very important as both systems work very differently and require different approaches.
- Materials used in your property. Originally, your traditional building was constructed of masonry set, pointed, and possibly plastered and/or rendered in lime-based products which allow moisture movement. However, it is quite likely that it was more recently maintained or altered using impermeable materials such as cement, water-proof membranes or insulation, which may have had an adverse effect on the performance of your building.
- Current condition of your building. A poorly maintained building (e.g. draughty windows, eroded mortar joints, faulty rainwater goods) can perform significantly worse than one that is well maintained.
- User behaviour. Modern lifestyle expectations such as open-plan living, ‘high’ indoor temperatures and lack of regular natural ventilation can lead to surface condensation and generally low comfort levels, leading to the desire for increased energy input.
- Whole house approach. Any retrofitting works (or change in user behaviour) will result in a reaction, and it may not be the one you have aimed for. To avoid unwanted outcomes, all potential risks will need to be very carefully assessed before embarking onto any works. The performance of your whole building – and not just isolated parts – needs to be considered, as well as its wider context, how it relates to the outside (weather exposure, topography/ ground levels), and the rooms within, how these are used and by whom (room type, people behaviour and health issues, building services). Without having the complete picture, it is far more likely that things will go wrong.
Sustainable Traditional Building Alliance - Whole House Approach [external link]
Essential first steps
The most obvious and lowest-risk interventions are restoring your traditional building’s fabric back to its originally intended performance (i.e. to its ‘default setting’) and using the building as it was designed to be used. As a result (and once it has dried out), it should perform well in terms of energy efficiency.
Therefore consider the following points first, before contemplating more drastic measures:
- Undo any previous unsympathetic works. Examples: remove cement pointing and repoint with a lime mortar; or reinstate external lime render/wash
- Carry out repair or maintenance works. Examples: repair faulty rainwater goods; or draught-proof leaking windows
- Change how you use the building. Examples: open windows regularly for effective ventilation; cover exposed wall surfaces with timber panelling or wall hangings such as tapestries (the latter could be done temporarily over the cold months only); subdivide large spaces into smaller ones, maybe with sliding partitions or curtains for seasonal flexibility; lower the thermostats and wear additional layers of clothing.
Please keep in mind that for listed buildings, any interventions to the existing fabric may require consent, depending on the nature and scale of the works.
Going further: retrofitting
Any retrofitting works will carry a level of risk, and high-risk interventions based on no or insufficient information can result in severe consequences, which can be very costly, time-consuming and entirely unsustainable:
- by unnecessarily installing the new measures
- due to high energy bills resulting from under-performance
- by having to remove them (and the inconvenience of this)
In order to determine the level of risk of various retrofitting measures, the Sustainable Traditional Building Alliance (STBA) has provided a guidance wheel freely available online. They have also determined general risk levels of typical works:
- Insulation laid on interior face of external walls (very high risk)
- Insulation laid on exterior face of external walls (high risk)
- Suspended and solid floor insulations (high risk)
- Rafter insulation (medium risk)
- Loft insulation (low risk)
The higher the risk of an intervention, the more necessary it will be to first carry out on-site testing/monitoring and computer-modelling of various retrofitting measures.
Moreover, retrofitting measures must be precisely installed to the correct specification and detail, as otherwise problems can be occur (e.g. cold bridges).
This page was last updated in January 2024.